1. Field of the Invention
The present invention relates to a backlight unit, a display unit, and a television receiver, and in particular, the present invention relates to a backlight unit, a display unit, and a television receiver, all of which are provided with a diffusion plate that diffuses light emitted from a light source.
2. Description of the Related Art
Conventionally, there are known backlight units provided with a diffusion plate that diffuses light emitted from a light source (e.g., see JP-A-2005-135670). In JP-A-2005-135670, a backlight unit is provided with fluorescent tubes (light sources), a diffusion plate diffusing light emitted from the fluorescent tubes and having holes (catching portions) in a peripheral portion thereof, and with pulling means engaging with the holes in the diffusion plate and applying tension to the diffusion plate in the planar direction.
In such backlight units provided with fluorescent tubes (light sources) and a diffusion plate, generally, due to a rise in temperature when the fluorescent tubes are lit, a diffusion plate 100 warps like a barrel (see FIGS. 20A and 20B) or a saddle (see FIGS. 21A and 21B), and in addition the peripheral portion moves inward in the planar direction.
In the backlight unit disclosed in JP-A-2005-135670, by providing the pulling means that applies tension to the diffusion plate, it is possible to prevent the peripheral portion of the diffusion plate from moving inward in the planar direction, and thus to prevent, to a certain degree, warping in the diffusion plate caused by a rise in temperature when the fluorescent tubes are lit.
In the backlight unit disclosed in above-mentioned JP-A-2005-135670, however, moving of the peripheral portion of the diffusion plate inward in the planar direction can be prevented indeed, but no mechanism is provided that fixes (supports) the diffusion plate in the direction perpendicular to the planar direction of the diffusion plate. Thus, inconveniently, it is difficult to prevent the diffusion plate from deforming in the direction perpendicular to the planar direction of the diffusion plate. For this reason, there arises a problem whereby warping in the diffusion plate is difficult to prevent sufficiently. When warping occurs in the diffusion plate, inconveniently, there may be cases where the diffusion plate makes contact with a display panel, which is arranged so as to face the diffusion plate, and thus the surface pressure of the display panel varies, making it difficult to obtain satisfactory images, and where warping occurs also in an optical sheet, which is arranged on the diffusion plate, and thus achieving uniform brightness is made difficult.